High-power High-frequency Lead-acid Battery Charging Power Based On Soft-switching Technology

After reviewing the history and current condition of the battery charging power source, this paper mainly elaborates on the realization of the zero-voltage switching for the leading leg and zero-current switching for the lagging leg of the Full - bridge DC - DC Converter combining the phase-shifting control and soft-switching operating principle. Then an improved ZVZCS full bridge DC-DC converter with passive voltage clamping is proposed which embraces a widening load range for soft switching, decreasing additional losses for auxiliary resonant circuit and a reducing stress of the voltage and current for the switches.Based on the analysis of the quick charging theory and a variety of charging methods, a two-stage charging strategy was put forward. At the first stage, the fast charging method was adopted which combines the multi-section constant-current method and charging pulsant charging method. And at the latter stage, the constant-voltage method was used. Measures to avoid the polarization of the battery are taken during the whole process of charging. During the quick charging process, optimal current is made in accordance with the temperature and voltage of the battery and fuzzy control is used to control the current which contributes to an impressive flexibility and suitability of the battery. The PI control is employed at the later period which will increase the service life of the battery and improve the charging efficiency.The quick system in this paper is designed by employing the TMS320LF2407A chip which can be used to the charging lead-acid battery of electric locomotives. Up to now, software and hardware design have been finished. The simulation and the experiment show that the main circuit proposed in this paper was proved to have the good characters of the soft switch and has an optimistic perspective of application. At last, we also put forward some humble suggestions on this subject.